Apparatus for the control of highway crossing signals



June 26, 1945. EQM. ALLEN 2,379,209

APPARATUS FOR THE CONTROL OF HIGHWAY CROSSING SIGNALS Original Filed Dec. 4, 1942 g \x Qt I It) IN INVENTOR &PZ M 141/912: By N AIL; ATTORNEY Patented June 26, 1945 APPARATUS FOR THE CONTROL OF HIGHWAY CROSSING SIGNALS Earl M. Allen, Swissvale, Pa., assignor to The Union Switch & Signal Company, Swissvale'; Pa., a corporation of Pennsylvania Original application December 4, 1942, Serial No.

467,840. Divided and this application July 11,, 1944, Serial No. 544,368 7 6 Claims. (Cl. 246-130) My invention relates to apparatus for the con trol of highway crossing signals, and has particularreference to the organization of such appae ratus into novel and improved systems controlled by railway traffic for operatin highway crossing signals.

This application is a division of my co-pending application, Serial No. 467,840, filed on December 4, 1942, for Apparatus for the control of highway crossing signals.

In highway crossing signal systems of the type employed for a stretch of track over which traflic operates in either direction, directional control means are employed to obtain operation of the crossing signal while a train approaches the crossing and to prevent operation when the train recedes from the crossing. In the ordinary forms of such systems, it is customary to employ two approach sections one on either side of the crossing and to arrange the directional control means to select the traflic direction whenever either approach section becomes occupied with the other approach section vacant. In other words, the directional control of the signal is usually established whenever either approach section is the first occupied and the apparatus then functions to prevent any train which occupies the other approach section during the time that the first is still occupied, from causing operation of the signal after the first section becomes vacant. These systems provide proper protection where only a single train is involved or where a plurality of trains operating in the same direction simultaneously occupy the two approach sections, that is, the systems function to cause operation of the signals while any train occupies the first-entered approach section and prevents operation after the first section becomes vacant either by the train in that section proceeding across the crossing and occupying the other approach section in receding from the crossing, or by the train reversing its direction of movement in the firstsection to recede from the crossing through the first section.

Where, however, trains operating in opposite directions concurrently occupy both approach sections and particularly where track switches are provided in or near the approach sections,

then the usual forms of crossing signal control systems are subject to improper operation such as either or both preventing signal operation when a train approaches the crossing and per-' mitting operation of the signal when atrain is receding from a crossing after having passed that crossing. For example, if the first entered approach ection is occupied by a first train and a second train operating, in the opposite direction enters the other section, then operation of the signalfornthe second train will be prevented or locked out if the first train vacates the first section either by being switched away from that section or by reversing its direction and receding from the crossing through the first ection. In other words, operation of the signal will be terminated when the first train vacatesthe first section, even though the second train is approaching the crossing. Under the particular conditions assumed, operation of the signal will usually be efiected by the second train after it reaches the crossing and enters the first approach section, but of course theoperation of-the signal when the second train recedes from the crossing through the firstsection has no useful function and is in fact improper.

I am aware that it has been proposed heretofore to provide crossing signal control systems of the class arranged to provide proper. protection where trains operating in opposite directions concurrently occupy both approach sections, and an object of my present invention, is to provide novel and improved highway crossing signal control systems of the class described.

.Another object of my present invention is to provide novel and improved crossing signal control systems arranged to prevent switching or other, irregular moves from interfering with operation of a crossing signal.

A further object is to provide novel and improved crossing signal systems incorporating means arranged to lock out operation of the signals only when the train proceeds across the crossing.

' An additional object is to provide novel andimproved means in a signal system for efiecting proper operation of a signal by at times varying the relative release periods of two control relays.

A further object is to provide novel and improved means for attaining proper operation of a crossing signal under various different conditions of movements of trains in the approach sections. In practicing the invention, the aboveementioned and other important objects and characteristic features of my invention which will become readily apparent from the following description are attained by providing two approach track sections separated from each other by a detector track section, and by controlling two control relays by three track relays in such a'manner that the relative release intervals of the two control relays are varied to establish a lock-out of one of the control relays only when the detector section with suitably distinguishing prefixes. Section 21.

is intersectedat grade by a highway H, and will be termed hereinafter a detector section. Section IT through which an eastbound" train, operatin from left to right as viewed in the drawing, must operation of the signal when the train clears the I detector section and occupies the other approach section in receding from the intersection. For example, if an eastbound train enters section IT, relay ITR releases to interrupt at the front point of contact 30 the previously traced energizing circuit of relay EPR, whereupon that relay in turn releases to close its back contact 34 and energize signal XS. Relay EPR also completes an alternate circuit for the other relay WPR, which circuit extends from terminal B through back contact 36 of relay EPR, front contact 33 of relay 2TB and the winding of relay WPR to terminal C. Relay I'I'R also energizes one winding of polar relay PR and relay INTESR over a circuit extending from terminal B through the back point of contact 30 of relay ITR, back con- I tact 31 of relay EPR, back contact 38 of relay travel in approaching the intersection will be termed the eastbound approach section, while the other section 3T through which westbound trains'operate in approaching the intersection will be termed the westbound approach section.

Each of the sections is -provided with av track circuit comprising a suitable source of current, such as a battery 3, and a track relay designated by the reference characterTR with a prefix corresponding to the prefix of the associated section. Each approach track relay has associated therewith a time element relay TER, two time element stick relays R'IESR and NTESR, andthe winding of a control relay of aninterlockin'g relayXR. Relay XR. may for example be of the type shown'in Letters Patent of the United States No. 1,799,629, granted April 7, 1931, to W. K. Lockhart and T. J. OMeara, and itcomprises two control relays EPR and WPR and aninterlocking machanism actuated by the armatures of the relays and arranged so that when either armature'isthe first to be released, the interlocking mechanism isactuated to a' position wherein it engages the other armature-to prevent it from dropping to afull down position if theother armature is released when the first is still released. A two-winding polar relay PR of the magnetic stick type also is providedfor connecting a. snub circuit path across the terminals-of relay EPRor WPR, as willbe made clear presently.-

Located at the intersection of: highway H and the stretch of track is a highway crossing signal of any suitable form, such as, forexample, an audible signal in the form of an electric bell XS. The bell is provided with anobvious energizing circuit completed whenever back contact 34 of relay EPR or back contact 35 of'relay WPR is closed.

In the normal condition of the apparatus, sections IT, IT and 3T are vacant so that relays ITR, 2TH, and ITR are picked up;v relay EPR is energized over a circuit which maybe traced from terminal B through the front point of contact30 of relay I'I'R, front contact 31 of relay 2TB. and the winding of relay EPR to terminal C; and relay WPR also lsenergized over a circuit which extends from terminal B through the'front point of contact 32 of relay 3TB. front contact 33 of relay 2TB. and the winding. of relay WPR to terminal C. Under these normal. conditions, the

' signal XS is of course deenergized.

For a train movement through all three sections, the apparatus operates in accordance with the usual custom to initiate operation of the signal when the train enters an approach section, maintains that operation when the train occupies the detector section, and prevents or locks out IRTESR, back or checking contact 39 of relay ITER, and then through two alternate paths one comprising back contact 40 of relay IN'I'ESR and the left-hand winding (as viewed in the drawing) of relay PR to terminal C, and the other circuit path comprising back contact H of relay I'IR, front contact 42 of relay 2TB, and the winding of relay INTESR to terminal C. The energizetion of the left-hand winding of relay PR at this time causes it to operate its polar contact 43 to its left-hand position (as viewed in the drawing) wherein an obvious snub circuit is completed for connecting resistor 44 across the terminals of relay WPR, while relay INTESR picks up to complete a circuit extending from terminal B through front'contact 45 of relay INTESR, back contact 46 of relay IRTESR and the operating element of relay ITER to terminal C. The time element relayI'I'ER accordingly becomes energized and opens its checking or back contact 39. When this happens, the previously traced circuits for relays'PR and INTESR are interrupted but relay PR remains in its left-hand position because of its magnetic stick features while relay INTESR is held energized over a stick circuit which extends from terminal B through the front point of contact 40 of relay INTESR, back contact ll of relay I'I'R, front contact 42 of relay ZTR and the Winding of relay IN'I'ESR to terminal C, The time contact 41 of relay ITER is adjusted to close after a, time interval substantially longer than that required for a train under ordinary conditions of operation to traverse section IT and enter section 2T. If, as has been assumed heretofore, the train makes a through move without passing in section IT, then section 2T will be entered by. the train before relay ITER closes its contact 41, and when relay 2TB. drops it interrupts the energizing circuit of relay INTEBR at frontcontact 42, whereupon relay INTESR releases to deenergize relay ITER at front contact 45. In addition, front contact 33 of relay 2TB interrupts the previously traced energizing circuits for relay.WPR and that relay accordingly releases its armature which is engaged by the interlocking mechanism and prevented from closing its back contacts.

When, the train enters section 3T, relay 3TR releases but this action has no useful function at this time. When, however, the train vacates section IT and relay 2TR picks up, relay EPR becomes energized over its previously traced circuit to terminate operation of signal XS, while relay 3TB. retains relay WPR deenergized and as a result the armature of the latter relay remains latched up until the train vacates section 3T. When this happens, relay 3TB picks up in turn to pick up relay WPR, and the apparatus is restored to its normal position.

The apparatus will function in a correspon ingly similar manner for a through movement of a westbound train, as will be apparent froman inspection of the drawing and further detailed explanation is deemed unnecessary except to point out that when the Westbound train enters section 3T and releases relay 3TR, the front point of contact 32' of relay 3TR opens to release relay WPR whereupon back contact 35 of relay WPR closes to energize signal XS while back contact 44 of relay WPR closes to complete a circuit extending from terminal B through back contact 44 of relay WPR, front contact 3I of'relay ZTR and the winding-of relay EPR to terminal C. Theback point of contact 32 of relay 3TR also closes to energize relays PR and 3NTESR over a circuit extending from terminal 13 through the back point of contact 32 of relay 3TR, back contact 49 of relay WPR, back contact 50 of relay 3RTESR, back contact I of relay 3TER, and then through back contact 52 of relay 3NTESR and the right-hand winding of relay PR to terminal C or through back contact 53 of relay 3TR, front contact 54 of relay 2TR, and the winding of relay 3NTESR toterminal C. Relay 3NTESR accordingly picks up and closes its front contact 55 to complete a circuit extending from terminal B through that contact, back contact 56 of relay 3RTESR and the winding of relay 3TER to terminal C; while relay PR shifts its polar'contact 43 to its right-hand position wherein an obvious circuit is completed for connecting resistor 58 across the-terminals of relay EPR. Assuming that the westbound train enters section 2T before front contact 59 of relay 3TER closes, winding WPR is retained deenergized as long as the train occupies section 3T or 2T, while the armature of relay EPR is released to its latched up position when front contact 3| of relay 2TR opens when the train occupies section 2T. The armature of relay EPR is maintained latched-up by relay ITR being released until the train vacates section IT, whereupon relays ITR and EPR pick up and the apparatus is restored to its normal condition The snub circuits applied to the windings of relays EPR and WPR function to provide correct operation of signal XS for opposing 0r switching movements on the stretch. For example, if a train enters an approach section and pauses for a time therein, it is undesirable to continue opera tion of signal XS for the entire interval and hence the apparatus is arranged to terminate operation of the signal after a predetermined interval, and to restart such operation if thetrain enters detector section 2T or if another train enters the other approach section. Thus, if an eastbound train enters section IT and pauses therein, relay ITR releases to deenergize relay EPR so that operation of signal XS is initiated and the previously traced auxiliary energizing circuit of relay'WPR is completed through back contact 36 of relay EPR and front contact 33 of relay 2TR. In addition, the left-hand winding of polar relay PR is energized over its previously traced circuit to shift its polar contact 43 to its left-hand position wherein it connects resistor 44 across the terminals of relay WPR, while relay INTESR picks up over its previously traced circuit and energizes relay ITER over its circuit including front contact 45 of relay INTESR and the'back point of contact 46 of relay IRTESR.

With the apparatus of my invention in the condition'just described, further operation of the apparatus will be described in connection with different train movements;

(1) If the trainreverses its direction and ya- Oates section IT prior to relay ZITER closing its front contact'41, then relay I.'I'R picks up to energize relay EPR and that relay picks up to. terminate operation ofsignal XS.. Re1ay-ITR also opens, its back contact 4| to-deenergize relay INTESR, whereupon that relay releases to deenergiz relay ITER; Relay ITER is slow in closing its checkingor back contact 39, and the apparatus willnot restoreto its-normal condition until that back contact closesso that if the train reenters section IT before back contact 39 of relay ITER closes, then relay EPR is released toim itiate operation of signal XS, but. relaysPR and IN'I'ESR remain deenergized at bELCkjQOIllZflCbB of relay ITER. After thatback contact closes,

relays PR and INTESR become energized and relay INTESR, in turn energizesyrelay ITER. Thisarrangement insures thatthe full timing action of relay ITER must elapse for each train entering the section, and -,D 1e,vents -a train:from utilizing a portion of the time measured by relay ITE'R for a previous train. In other words, relay ITER must go through its entirepick-up cycle for each train, and to insure this the relay must be restored to its normal condition before its pick-up cycle can be commenced, v

(2) If the train occupies section IT for the full interval required for relay ITER to close its front contact 41, relay IRTESR picks upover a circuit which extends from terminal B through front contact 45 of relay INTESR; front contact 41 of relay ITER and the Winding of relay. IRTESR to terminal C. Relay IRTEESR accordingly picks up and'closes the front point of, its contact 46 to complete its own stick circuit which is connected to terminal. B at ,front contact 45 of relay INTESR, and also opens, the back point o f con-. tact .46 to'deenergize relay I'I'ER, which relay accordingly opens its front contact 41. When back contact 39 of relay ITER closes at the end of its slow release, interval, relay EPR becomes energized over a circuit extending from terminal B through front contact 40 of relay INTES R, back contact 39 of relay vI'IER, front contact 38 of relay IRTESR, front contact 3! 0f r'eIayZTR and thel'winding of relay EPR to terminal C. Relay EPR accordingly picks up to open its back contact 34 and thus terminate operation of signal XS, to open its back contact 36 and thus open the alternate circuit of relay WPR, and also to release the interlocking mechanism of relay XR to cause it to assume its normal condition. I j' 1 (3) If, after operation of signal XS has been terminated by the time element apparatus in the foregoing manner, the train vacates section IT at its remote or Ieft-handend, as viewed in the drawing, then relay ITR'picks up to close its front contact 30 and'complete'the normal energizing circuit for relay'EPR, and back contact 4I also opens to interrupt the stick circuit for relay INTESR whereupon that relay releases to release relay IRTESR, and the apparatus is restored to its normal condition. 1

(3a) If, on the other hand, after the operation of signal XS has been terminated by relay ITER. in the manner described in detail hereinbefore, and the train in section IT enters section 2T, then relay 21R is released and relays EPR and WPR are simultaneously deenergized at front contacts 3| and 33 of relay 2TR, respectively. Relay 'WPR is, however, provided with 'a snub circuit which includes'polar contact 43*of relay PR in-its left-hand position and which connects resistor 44 across the terminals the winding of relay WPR and thus provides aclosed circuit path whereinvthefluxin the winding of relay 'WPR circulateslto hold up the armature of that relay for an interval oi time suillcient to enable the armature oi relsylllPR to release to its tull down position and actuate the mechanical looking mechanism into the path of the armatureot relay WPR to latch up that armature when it finally releases. when the train enterl section 3T, relay 8TB. of course releasesto hold? the armature oi relay WPR released in its latchedup position after the train vacates'sectioniT and relay 2TB picks up to reenergize the-winding oi relay EPR. The timing apparatussssociated I with relay 3TB. is not active at this time because back contact 40 or relay WPR is open, and back contact "also is open so that operation of signal xs is prevented when the train recedes from the crossing. After the train vacates sectional, relay I'I'R. picks up to reenersize relay WPR and the apparatus is restored to its normal condition.

It is to be noted that when the eastbound train enters section 21' after the timing apparatus has terminated operation of signal relay INTESB, becomes deenergized at front contact I2 01' relay 2TB, and relay INTESR in turn deener gizes relay IR'I'ESR at front contact 45 This operation restores the timing apparatus of section I'Ito its and closes its front contact l2, whereupon relay IN'I'ESR. then becomes energized to energize relay ITER and start the timingperiod forthe second train. I II, with an eastbound train occupying section IT so that relays [TR and EPR; are released, polar relay PR is in its left-hand position to snub winding WPR, and the timing apparatus associated with relay ITR, is active, 9. westbound train enters section 3T, relay 3TB will release but relay WPR will be held up at time over an auxiliary circuit that includes back contact 36 of relay EPR. (a) Should the train inse'ction IT reverse its direction of travel and vacate the section at its left-hand end before relay, ITER closes its front contact 41, then relay ITR; will pick up to open its front contact I and deenergize relay INTESR. Relay INI'ESR theree upon will release to open its front contact 45" and deenergize relay ITER. Also, the front point of contact of relay I TR; will close to complete the normal energizing circuit of relay EPR, and that relay in turn will pick up to open its back contact and thereby open the previously men tioned auxiliary circuit for the winding of relay WPR. Relay WPR accordingly will become deenergized but since it is snubbed at this time it is slow to release and does not release until after the armature of relay EPR picks up and the locking mechanism assumes its normal position. When the armature of WPR does release, however, it will drop to its full down position wherein back contact 35 establkhes the operating circuit for bell X8, and the mechanical lockingarrangement is actuated into the path oi the armature oi relay E28 so that when the westbound train enters section 2'1 and relay 2TB releases, the resultant release oi. relay EPR will result inits armature being latched up. When the train enters section IT, relay ITR will release to hold the armature of relay EPR. in its latched position after section 2T is'vacated and relay 2TB. picks up to energize relay WPR and thereby terminate operation of the signal. The apparatus is of course restored to its normal condition when the westbound train vacates section IT and relay I'I'R. picks up to energize relay EPR.

(11) Should the first train in section IT occupy that section (with section 3'! also occupied by a second westbound train) for an interval sufllcient to enable relay I'IER to close its fruit contact 41, then-when relay IRTEBR picks up, relay ITERwill become deenergized and after it closes its back contact 38, relay EPR will become energized over its previously traced circuit including the front point of contact 40 of relay INI'ESR, back contact 38 of relay I'l'lm, the front point of contact 38 of relay IR'IESR, front contact SI of relay ZTR and the winding 0! relay EPR. When relay EPR picks up it transiers the control of signal XS to the other relay" WPR, in substantially the same manner as that hereinbeiore described in detail in connection withtlie pick-up of relay I'I'R when the eastbound train vacates section IT at its left-hand end, and it follows that after the eastbound train vacate: section IT, the signal will be properly controlled for a movement of the westbound train over sections IT, IT, and IT.

The apparatus will function for the various possible movements or a westbound train either alone or in conjunction with the eastbound train in substantially the same manner as that pointed out in detail hereinbeiore for the various move ments of an eastbound train. That isto any, the timing apparatus associated with relay 3TR is arranged to become active when the section is entered, and it will terminate operation oi signal XS if the westbound train occupies the section for an interval of time longer than the pick-up period of relay STER. Also, when a westbound train enters section 3T, relay PR is shifted to its right-hand. position wherein. the winding of relay EPR is snubbed sothat operation- 01 signal XS may be transferred to an eastbound train or be retained by the westbound train according as section IT is entered by an eastbound or a westbound train, respectively.

From the foregoing, it is readily apparent that the apparatus embodying my. invention is'arranged so as to employ two controlrelays and lock one or the other relay out of control of the signal only when the detector section becomes occupied. In addition, it is to be noted that the look-out of a relay is dependent at times uD'On the relative release intervals of the relay and that these release intervals are selectively controlled so as to govern the closure of the, back contacts and establish the correct directional control of the signal under the various conditions of train movements. Although I have herein shown and described only one form of apparatus for the control of highway crossing signals embodying my lnven-, tion, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

b 1. In combination with a stretch of railway track intersected by a highway and provided at the intersection with a highway crossing signal, an interlocking relay comprising two control relays one for each direction of trafiic over said stretch and each normally energized in a pickup circuit, an energizing circuit for said signal including a back contact of either of said control relays, means controlled by a train on said stretch approaching said intersection for interrupting the pick-up circuit of the control relay associated with that trains direction of traffic, an means controlled by a back contact of either of said control relays for completing an alternate circuit for the other control relay and for increasing the release interval of said other con-' trol relay.

2. In combination with a stretch of railway track intersected by a highway and provided at the intersection with a highway crossing signal, an interlocking relay comprising two control relays one for each direction of trafiic over said stretch and each normally energized in a pickup circuit, an energizing circuit for said signal completed at a back contact of either of said control relays, means controlled by a train -on said stretch approaching said intersection for interrupting the pick-up circuit of the control relay associated with that trains direction of traffic, means controlled by a back contact of either of said control relays for increasing the release interval of the other control relay, timing means controlled by a back contact of either of said control relays and efiective at the end of a predetermined time interval for completing an alternate pick-up circuit for'that control relay, and means controlled by a train entering said intersection for deenergizing both of said control relays.

3. In combination with a stretch of railway track intersected by a highway and provided at the intersection with a highway crossing signal, an interlocking relay comprising two control relays one for each direction of traffic over said stretch and each normally energized in a pick-up circuit, an energizing circuit for said signal complete at a back contact of either of said control relays, means controlled by a train on said stretch approaching said intersection for interrupting the pick-up circuit of the control relay associated with that trains direction of trafiic, means controlled by a back contact of either of said control relays for increasing the release interval of the other control relay, means controlled by a back contact of either of said control relays for completing an alternate energizing circuit for the other control relay, timing means controlled by a back contact of either of said control relays and effective at the end of a predetermined time interval for completing an alternate pick-up circuit for that control relay, and means controlled by a train entering said intersection for deenergizing both of said control relays.

4. In combination with a stretch of railway track divided into two approach sections separated from each other by an intermediate section intersected at grade by a highway, a highway crossing signal at said intersection, a track circuit including a track relay for each of said sections, an interlocking relay comprising two control relays, means for normally energizing one control relay over a circuit including a front contact of the track relay of one of said approach sections and a front contact of the track relay of said intermediate section, means for normally energizing the other control relay over a circuit including a front contact of the track relay of the other approach section and a front contact of the track relay of said intermediate section, two alternate energizing circuits one for each control relay and each including a front contact of the track relay of said intermediate section and a back contact of the other control relay, means controlled by each approach track relay and including a back contact of its associated control relay for connecting a resistor across the terminals of the other control relay for delaying the release of said other control relay, and an energizing circuit for said highway crossing including a back contact of either control relay.

5. In combination with a stretch of railway track divided into two approach sections separated from each other by an intermediate section intersected at grade by a highway, a highway crossing signal at said intersection, a track circuit including a track relay for each of said section's, an interlocking relay comprising two control relays, means for normally energizing one control relay over a circuit including a front contact of the track relay of one of said approach sections and a front contact of the track relay of said intermediate section, means for normally energizing the other control relay over a circuit including a front contact of the track relay of the other approach section and a front contact of the track relay of said intermediate section, two alternate energizing circuits one for each control relay and each including a front contact of the track relay of said intermediate section and a back contact of the other control relay, means controlled by each approach track relay and including a back contact of its associated control relay for connecting a resistor across the terminals of the other control relay for delaying the release of said other control relay, timing means controlled by each approach track relay and including a back contact of its associated control relay for providing at the end of a predetermined time interval an alternating energizing circuit for that associated control relay, and an energizing circuit for said highway crossing including a back contact of either control relay.

6. In combination with a stretch of railway track divided into two approach sections separated from each other by an intermediate section intersected by a highway and provided at the intersection with a highway crossing signal, a track circuit including a track relay for each of said sections, two control relays one for each direction of trafiic over said stretch, means controlled by the track relay of the approach section first entered by an eastbound train approaching the intersection for normally energizing the eastbound control relay, means controlled by the track relay of the approach section first entered by a westboundrtrain approaching the intersection for normally energizing the westbound control relay, means controlled by the track relay of said intermediate section for controlling the energizing circuits of both of said control relays, means controlled by a back contactof either of said control relays for increasing the release period of the other of said control relays, means controlled by the release periods of said control relays for governing the closure of the back contacts of such relays, and an energizing circuit for said signal completed at a back contact of either of said control relays.

EARL M. ALLEN. 

